The present invention relates to the surfacing of concrete, and more particularly, concerns methods and apparatus for supporting and controlling elevation of a concrete surfacing screed.
In the pouring of concrete having level or generally level surfaces, it is common to establish a pair of spaced, parallel screed bars or rails having upper (or lower) surfaces at a fixed elevation above the desired surface of the finished concrete. The concrete is poured between screed bars to a level slightly above the desired finished level, and thereafter a screed, resting upon the screed bars or rails, is moved over the surface of the concrete for the purpose of both vibrating the wet, uncured material and achieving a final or near final finished surface.
Each screed bar or rail is supported upon a series of screed chairs or similar supports, which are placed upon the ground or other surfaces upon which the concrete is to be poured. The screed supports provide means for achieving vertical adjustment so that the screed bar will be at the desired elevation throughout its length. At least partly because the weight of a vibrating screed may be great, the screed chairs must be strong and have good lateral stability to avoid tilting. Thus, the chairs often have a number of legs which collectively support the screed bar and yet extend laterally outward for improved support.
Where concrete is being poured upon a surface having various types of obstructions (such as columns, posts, pipes, reinforcing steel, and the like) or where the surface is a corrugated metal sheet (such as commonly employed Robinson decking), it is difficult to properly position all of the required screed chairs or supports without encountering interference between the support legs and the obstructions. The problem is enhanced by the lateral extent of the legs required for stability, so that each screed chair necessarily spans a relatively large lateral area.
In the placement of the screed support upon corrugated Robinson decking, the support legs are positioned within the grooves to hold the screed support above the ridges of the decking corrugations. The width of the ridges and grooves in Robinson decking may vary from one type of decking to another, and, therefore, screed supports may be required to be built to accommodate specific corrugation spacing. For this reason, a screed chair for decking of one corrugation width may not be readily used with decking of a different corrugation width.
Accordingly, it is an object of the present invention to provide a screed support assembly that avoids or minimizes the above-mentioned problems.